## Summary
If you paste in the TOML for our default configuration (from the docs),
it's rejected by our JSON Schema:
It seems like the issue is with:
```toml
# Set the line length limit used when formatting code snippets in
# docstrings.
#
# This only has an effect when the `docstring-code-format` setting is
# enabled.
docstring-code-line-length = "dynamic"
```
Specifically, since that value uses a custom Serde implementation, I
guess Schemars bails out? This PR adds a custom representation to allow
`"dynamic"` (but no other strings):
This seems like it should work but I don't have a great way to test it.
Closes https://github.com/astral-sh/ruff/issues/9630.
b0d6fd7343